The present invention relates to an underwater communication system.
There are known underwater communication systems, used for monitoring underwater breathing apparatus for example, which comprise means for transmitting data from an underwater breathing apparatus to a receiving unit, which can be a portable computer with a display unit, such as a wrist computer, used by a diver, thus making the diver aware of data such as the duration of decompression phases, the amount of air remaining in the cylinders, and the like.
U.S. Pat. No. 5,738,092 describes a monitoring device for portable breathing apparatus, comprising a pressure gauge by means of which the pressure in the pressurized container of the breathing apparatus is detected, and comprising a transmitter by means of which a signal corresponding to the detected pressure is transmitted at regular intervals. The transmitter is also provided with a signal generator device which generates an identification signal which is characteristic of the transmitter. The pressure signal and the identification signal are received and verified by a receiver. If the identification signal matches a comparison signal stored in the receiving device, the measured pressure value is shown on the display.
Such known underwater communication systems have a number of drawbacks: in the first place, the communication between the wrist computer and the pressure sensor of the cylinders is unidirectional, in the sense that the data travel solely from the pressure sensor of the breathing apparatus to the wrist computer, in such a way that, for example, the wrist computer has to wait for the data sent by the pressure sensor on each occasion, without being able to request it at any time; furthermore, the identification and data signals sent by the transmitter are in clear, and therefore may be incorrectly intercepted, for example by another communication system belonging to another diver or groups of divers.
The object of the present invention is therefore to provide an underwater communication system which overcomes the drawbacks of the known underwater communication systems cited above; which enables one or more transmitter units and one or more receiver units to communicate in a bidirectional way; in which the data exchanged by the receiver unit with the transmitter unit are encrypted, and therefore can be understood only if the apparatus of the system has decryption keys; and which can be used to create an underwater communication network among a plurality of apparatus or units belonging to a diver, for example a wrist computer, the pressure sensor of the cylinders, and the inflatable jacket worn by the diver.
This object is achieved by the present invention by means of an underwater communication system comprising a plurality of communication modules, each provided with a microprocessor, a memory, a transmitter and a receiver unit, said communication modules being incorporated in an underwater computer and in a plurality of underwater equipment devices, characterized in that the underwater computer and the underwater equipment devices form an underwater master/slave communication network for short and long ranges, in which each device forms a node and communicates in a bidirectional way with the other nodes of the network administered by a main underwater computer or master unit, each node of the network being identified by a unique identification code which is assigned dynamically by the master unit of the network and being provided with at least one of said communication modules for short-range communication and, if necessary, with at least one communication module for long-range communication, a data and message transmission protocol being provided for said network for the administration of the network for the operations of connection, detection of the devices present in the network, and short-range and long-range data transmission.